Method for transmitting a power headroom reporting in wireless communication system and a device therefor

ABSTRACT

The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for transmitting a power headroom reporting in wireless communication system, the method comprising: generating a PHR MAC CE including multiple PH fields for a serving cell; and transmitting the PHR MAC CE, wherein the PHR MAC CE includes an octet containing a single PCMAX field associated with the multiple PH fields for the serving cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage application under 35 U.S.C. § 371 of International Application No. PCT/KR2018/008026, filed on Jul. 16, 2018, which claims the benefit of U.S. Provisional Application No. 62/535,218, filed on Jul. 20, 2017. The disclosures of the prior applications are incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system and, more particularly, to a method for transmitting a power headroom reporting in wireless communication system and a device therefor.

BACKGROUND ART

As an example of a mobile communication system to which the present invention is applicable, a 3rd Generation Partnership Project Long Term Evolution (hereinafter, referred to as LTE) communication system is described in brief.

FIG. 1 is a view schematically illustrating a network structure of an Evolved Universal Mobile Telecommunications System (E-UMTS) as an exemplary radio communication system. The E-UMTS is an advanced version of a conventional Universal Mobile Telecommunications System (UMTS) and basic standardization thereof is currently underway in the 3GPP. E-UMTS may be generally referred to as a Long Term Evolution (LTE) system. The communication network is widely deployed to provide a variety of communication services such as voice (VoIP) through IMS and packet data.

Referring to FIG. 1, the E-UMTS includes a User Equipment (UE), eNode Bs (eNBs), and an Access Gateway (AG) which is located at an end of the network (E-UTRAN) and connected to an external network. The eNBs may simultaneously transmit multiple data streams for a broadcast service, a multicast service, and/or a unicast service.

One or more cells may exist per eNB. The cell is set to operate in one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz and provides a downlink (DL) or uplink (UL) transmission service to a plurality of UEs in the bandwidth. Different cells may be set to provide different bandwidths. The eNB controls data transmission or reception to and from a plurality of UEs. The eNB transmits DL scheduling information of DL data to a corresponding UE so as to inform the UE of a time/frequency domain in which the DL data is supposed to be transmitted, coding, a data size, and hybrid automatic repeat and request (HARQ)-related information. In addition, the eNB transmits UL scheduling information of UL data to a corresponding UE so as to inform the UE of a time/frequency domain which may be used by the UE, coding, a data size, and HARQ-related information. An interface for transmitting user traffic or control traffic may be used between eNBs. A core network (CN) may include the AG and a network node or the like for user registration of UEs. The AG manages the mobility of a UE on a tracking area (TA) basis. One TA includes a plurality of cells.

Although wireless communication technology has been developed to LTE and NR based on wideband code division multiple access (WCDMA), the demands and expectations of users and service providers are on the rise. In addition, considering other radio access technologies under development, new technological evolution is required to secure high competitiveness in the future. Decrease in cost per bit, increase in service availability, flexible use of frequency bands, a simplified structure, an open interface, appropriate power consumption of UEs, and the like are required.

As more and more communication devices demand larger communication capacity, there is a need for improved mobile broadband communication compared to existing RAT. Also, massive machine type communication (MTC), which provides various services by connecting many devices and objects, is one of the major issues to be considered in the next generation communication (NR, New Radio). In addition, a communication system design considering a service/UE sensitive to reliability and latency is being discussed. The introduction of next-generation RAT, which takes into account such Enhanced Mobile BroadBand (eMBB) transmission, and ultra-reliable and low latency communication (URLLC) transmission, is being discussed.

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies in a method and device for transmitting a power headroom reporting in wireless communication system.

In LTE, the Power Headroom Reporting (PHR) procedure is used to provide the serving eNB with information about the difference between the nominal UE maximum transmit power and the estimated power for UL-SCH transmission and also with information about the difference between the nominal UE maximum power and the estimated power for UL-SCH and PUCCH transmission on SpCell and PUCCH SCell. And the eNB can use the PHR report as input to the scheduler. Based on the available power headroom the scheduler will decide a suitable number of PRBs and an appropriate MCS as well a correct transmit power adjustment.

In Rel-15, NR system supports the wider bandwidth (WB) or multi-beam operation.

The carrier performing the wider bandwidth operation can be composed of one or more bandwidth part(s) and each bandwidth part is associated with a specific numerology. In this operation, gNB can configure or activate a specific bandwidth part for a UE. According to the current RAN1 agreement, UE expects at least one DL bandwidth part and one UL bandwidth part being active among the set of configured bandwidth parts for a given time instant. In addition, for a single carrier WB UE, multiple active bandwidth parts with different numerologies can be configured for a UE simultaneously. In this WB operation, the gNB may require PH information per BWP in order to decide a suitable UL resource of a UE.

Further, to provide link robustness between UE and gNB for both downlink and uplink, there may be multiple beam pair links between UE and gNB, where a beam pair link comprises a UE TX beam and a gNB RX beam. By using the multiple beam pair links, the UE may be able to transmit or receive a data repeatedly, if necessary. RAN1 agreed that UE should be able to maintain links with multiple DL beam pair of one cell between multiple TRPs and the UE. For UL link robustness, it would be necessary to maintain multiple UL beam pair links between multiple TRPs and the UE. In particular, pathloss between multiple TRPs may be significantly different than pathloss in multiple links within a single TRP due to their locations. This may result in different resource allocations e.g., including transmit power, between multiple beam pair links.

The gNB should allocate the suitable UL resource for each beam pair based on the UE's PH information.

The technical problems solved by the present invention are not limited to the above technical problems and those skilled in the art may understand other technical problems from the following description.

Technical Solution

The object of the present invention can be achieved by providing a method for User Equipment (UE) operating in a wireless communication system as set forth in the appended claims.

In another aspect of the present invention, provided herein is a communication apparatus as set forth in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Advantageous Effects

This invention proposes to define a new PHR trigger event and a new PHR MAC CE format in order for a UE to transmit a PH information for a beam pair (BP) or bandwidth part (BWP) when a UE operates in multi-beam or wider bandwidth operation.

This invention proposes that a UE transmits one or more PH(s) for a single P_(CMAX) field in a PHR MAC CE in order to inform each PH for different UL beam pair or different numerology/bandwidth part of a serving cell.

It will be appreciated by persons skilled in the art that the effects achieved by the present invention are not limited to what has been particularly described hereinabove and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention.

FIG. 1 is a diagram showing a network structure of an Evolved Universal Mobile Telecommunications System (E-UMTS) as an example of a wireless communication system;

FIG. 2a is a block diagram illustrating network structure of an evolved universal mobile telecommunication system (E-UMTS), and FIG. 2b is a block diagram depicting architecture of a typical E-UTRAN and a typical EPC;

FIG. 3 is a diagram showing a control plane and a user plane of a radio interface protocol between a UE and an E-UTRAN based on a 3rd generation partnership project (3GPP) radio access network standard;

FIG. 4a is a block diagram illustrating network structure of NG Radio Access Network (NG-RAN) architecture, and FIG. 4b is a block diagram depicting architecture of functional Split between NG-RAN and 5G Core Network (5GC);

FIG. 5 is a diagram showing a control plane and a user plane of a radio interface protocol between a UE and a NG-RAN based on a 3rd generation partnership project (3GPP) radio access network standard;

FIG. 6 is a block diagram of a communication apparatus according to an embodiment of the present invention;

FIG. 7 is a diagram for signaling of power headroom reporting via a MAC CE;

FIG. 8a is examples for multiple beam pair links, and FIG. 8b is an example of PHR trigger in BWP activation/deactivation;

FIG. 9 is a conceptual diagram for transmitting a power headroom reporting in wireless communication system according to embodiments of the present invention;

FIG. 10 is an example of PHR trigger based on the BWP configuration; and

FIGS. 11 to 14 are examples for a PHR MAC CE for BP or BWP operation according to embodiments of the present invention.

BEST MODE

Universal mobile telecommunications system (UMTS) is a 3rd Generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). The long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.

The 3GPP LTE is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3G LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

Hereinafter, structures, operations, and other features of the present invention will be readily understood from the embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Embodiments described later are examples in which technical features of the present invention are applied to a 3GPP system.

Although the embodiments of the present invention are described using a long term evolution (LTE) system and a LTE-advanced (LTE-A) system in the present specification, they are purely exemplary. Therefore, the embodiments of the present invention are applicable to any other communication system corresponding to the above definition. In addition, although the embodiments of the present invention are described based on a frequency division duplex (FDD) scheme in the present specification, the embodiments of the present invention may be easily modified and applied to a half-duplex FDD (H-FDD) scheme or a time division duplex (TDD) scheme.

FIG. 2a is a block diagram illustrating network structure of an evolved universal mobile telecommunication system (E-UMTS). The E-UMTS may be also referred to as an LTE system. The communication network is widely deployed to provide a variety of communication services such as voice (VoIP) through IMS and packet data.

As illustrated in FIG. 2a , the E-UMTS network includes an evolved UMTS terrestrial radio access network (E-UTRAN), an Evolved Packet Core (EPC) and one or more user equipment. The E-UTRAN may include one or more evolved NodeB (eNodeB) 20, and a plurality of user equipment (UE) 10 may be located in one cell. One or more E-UTRAN mobility management entity (MME)/system architecture evolution (SAE) gateways 30 may be positioned at the end of the network and connected to an external network.

As used herein, “downlink” refers to communication from eNodeB 20 to UE 10, and “uplink” refers to communication from the UE to an eNodeB. UE 10 refers to communication equipment carried by a user and may be also referred to as a mobile station (MS), a user terminal (UT), a subscriber station (SS) or a wireless device.

FIG. 2b is a block diagram depicting architecture of a typical E-UTRAN and a typical EPC.

As illustrated in FIG. 2b , an eNodeB 20 provides end points of a user plane and a control plane to the UE 10. MME/SAE gateway 30 provides an end point of a session and mobility management function for UE 10. The eNodeB and MME/SAE gateway may be connected via an S1 interface.

The eNodeB 20 is generally a fixed station that communicates with a UE 10, and may also be referred to as a base station (BS) or an access point. One eNodeB 20 may be deployed per cell. An interface for transmitting user traffic or control traffic may be used between eNodeBs 20.

The MME provides various functions including NAS signaling to eNodeBs 20, NAS signaling security, AS Security control, Inter CN node signaling for mobility between 3GPP access networks, Idle mode UE Reachability (including control and execution of paging retransmission), Tracking Area list management (for UE in idle and active mode), PDN GW and Serving GW selection, MME selection for handovers with MME change, SGSN selection for handovers to 2G or 3G 3GPP access networks, Roaming, Authentication, Bearer management functions including dedicated bearer establishment, Support for PWS (which includes ETWS and CMAS) message transmission. The SAE gateway host provides assorted functions including Per-user based packet filtering (by e.g. deep packet inspection), Lawful Interception, UE IP address allocation, Transport level packet marking in the downlink, UL and DL service level charging, gating and rate enforcement, DL rate enforcement based on APN-AMBR. For clarity MME/SAE gateway 30 will be referred to herein simply as a “gateway,” but it is understood that this entity includes both an MME and an SAE gateway.

A plurality of nodes may be connected between eNodeB 20 and gateway 30 via the S1 interface. The eNodeBs 20 may be connected to each other via an X2 interface and neighboring eNodeBs may have a meshed network structure that has the X2 interface.

As illustrated, eNodeB 20 may perform functions of selection for gateway 30, routing toward the gateway during a Radio Resource Control (RRC) activation, scheduling and transmitting of paging messages, scheduling and transmitting of Broadcast Channel (BCCH) information, dynamic allocation of resources to UEs 10 in both uplink and downlink, configuration and provisioning of eNodeB measurements, radio bearer control, radio admission control (RAC), and connection mobility control in LTE ACTIVE state. In the EPC, and as noted above, gateway 30 may perform functions of paging origination, LTE-IDLE state management, ciphering of the user plane, System Architecture Evolution (SAE) bearer control, and ciphering and integrity protection of Non-Access Stratum (NAS) signaling.

The EPC includes a mobility management entity (MME), a serving-gateway (S-GW), and a packet data network-gateway (PDN-GW). The MME has information about connections and capabilities of UEs, mainly for use in managing the mobility of the UEs. The S-GW is a gateway having the E-UTRAN as an end point, and the PDN-GW is a gateway having a packet data network (PDN) as an end point.

FIG. 3 is a diagram showing a control plane and a user plane of a radio interface protocol between a UE and an E-UTRAN based on a 3GPP radio access network standard. The control plane refers to a path used for transmitting control messages used for managing a call between the UE and the E-UTRAN. The user plane refers to a path used for transmitting data generated in an application layer, e.g., voice data or Internet packet data.

A physical (PHY) layer of a first layer provides an information transfer service to a higher layer using a physical channel. The PHY layer is connected to a medium access control (MAC) layer located on the higher layer via a transport channel. Data is transported between the MAC layer and the PHY layer via the transport channel. Data is transported between a physical layer of a transmitting side and a physical layer of a receiving side via physical channels. The physical channels use time and frequency as radio resources. In detail, the physical channel is modulated using an orthogonal frequency division multiple access (OFDMA) scheme in downlink and is modulated using a single carrier frequency division multiple access (SC-FDMA) scheme in uplink.

The MAC layer of a second layer provides a service to a radio link control (RLC) layer of a higher layer via a logical channel. The RLC layer of the second layer supports reliable data transmission. A function of the RLC layer may be implemented by a functional block of the MAC layer. A packet data convergence protocol (PDCP) layer of the second layer performs a header compression function to reduce unnecessary control information for efficient transmission of an Internet protocol (IP) packet such as an IP version 4 (IPv4) packet or an IP version 6 (IPv6) packet in a radio interface having a relatively small bandwidth.

A radio resource control (RRC) layer located at the bottom of a third layer is defined only in the control plane. The RRC layer controls logical channels, transport channels, and physical channels in relation to configuration, re-configuration, and release of radio bearers (RBs). An RB refers to a service that the second layer provides for data transmission between the UE and the E-UTRAN. To this end, the RRC layer of the UE and the RRC layer of the E-UTRAN exchange RRC messages with each other.

One cell of the eNB is set to operate in one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz and provides a downlink or uplink transmission service to a plurality of UEs in the bandwidth. Different cells may be set to provide different bandwidths.

Downlink transport channels for transmission of data from the E-UTRAN to the UE include a broadcast channel (BCH) for transmission of system information, a paging channel (PCH) for transmission of paging messages, and a downlink shared channel (SCH) for transmission of user traffic or control messages. Traffic or control messages of a downlink multicast or broadcast service may be transmitted through the downlink SCH and may also be transmitted through a separate downlink multicast channel (MCH).

Uplink transport channels for transmission of data from the UE to the E-UTRAN include a random access channel (RACH) for transmission of initial control messages and an uplink SCH for transmission of user traffic or control messages. Logical channels that are defined above the transport channels and mapped to the transport channels include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and a multicast traffic channel (MTCH).

FIG. 4a is a block diagram illustrating network structure of NG Radio Access Network (NG-RAN) architecture, and FIG. 4b is a block diagram depicting architecture of functional Split between NG-RAN and 5G Core Network (5GC).

An NG-RAN node is a gNB, providing NR user plane and control plane protocol terminations towards the UE, or an ng-eNB, providing E-UTRA user plane and control plane protocol terminations towards the UE.

The gNBs and ng-eNBs are interconnected with each other by means of the Xn interface. The gNBs and ng-eNBs are also connected by means of the NG interfaces to the 5GC, more specifically to the AMF (Access and Mobility Management Function) by means of the NG-C interface and to the UPF (User Plane Function) by means of the NG-U interface.

The Xn Interface includes Xn user plane (Xn-U), and Xn control plane (Xn-C). The Xn User plane (Xn-U) interface is defined between two NG-RAN nodes. The transport network layer is built on IP transport and GTP-U is used on top of UDP/IP to carry the user plane PDUs. Xn-U provides non-guaranteed delivery of user plane PDUs and supports the following functions: i) Data forwarding, and ii) Flow control. The Xn control plane interface (Xn-C) is defined between two NG-RAN nodes. The transport network layer is built on SCTP on top of IP. The application layer signalling protocol is referred to as XnAP (Xn Application Protocol). The SCTP layer provides the guaranteed delivery of application layer messages. In the transport IP layer point-to-point transmission is used to deliver the signalling PDUs. The Xn-C interface supports the following functions: i) Xn interface management, ii) UE mobility management, including context transfer and RAN paging, and iii) Dual connectivity.

The NG Interface includes NG User Plane (NG-U) and NG Control Plane (NG-C). The NG user plane interface (NG-U) is defined between the NG-RAN node and the UPF. The transport network layer is built on IP transport and GTP-U is used on top of UDP/IP to carry the user plane PDUs between the NG-RAN node and the UPF. NG-U provides non-guaranteed delivery of user plane PDUs between the NG-RAN node and the UPF.

The NG control plane interface (NG-C) is defined between the NG-RAN node and the AMF. The transport network layer is built on IP transport. For the reliable transport of signalling messages, SCTP is added on top of IP. The application layer signalling protocol is referred to as NGAP (NG Application Protocol). The SCTP layer provides guaranteed delivery of application layer messages. In the transport, IP layer point-to-point transmission is used to deliver the signalling PDUs.

NG-C provides the following functions: i) NG interface management, ii) UE context management, iii) UE mobility management, iv) Configuration Transfer, and v) Warning Message Transmission.

The gNB and ng-eNB host the following functions: i) Functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling), ii) IP header compression, encryption and integrity protection of data, iii) Selection of an AMF at UE attachment when no routing to an AMF can be determined from the information provided by the UE, iv) Routing of User Plane data towards UPF(s), v) Routing of Control Plane information towards AMF, vi) Connection setup and release, vii) Scheduling and transmission of paging messages (originated from the AMF), viii) Scheduling and transmission of system broadcast information (originated from the AMF or O&M), ix) Measurement and measurement reporting configuration for mobility and scheduling, x) Transport level packet marking in the uplink, xi) Session Management, xii) Support of Network Slicing, and xiii) QoS Flow management and mapping to data radio bearers. The Access and Mobility Management Function (AMF) hosts the following main functions: i) NAS signalling termination, ii) NAS signalling security, iii) AS Security control, iv) Inter CN node signalling for mobility between 3GPP access networks, v) Idle mode UE Reachability (including control and execution of paging retransmission), vi) Registration Area management, vii) Support of intra-system and inter-system mobility, viii) Access Authentication, ix) Mobility management control (subscription and policies), x) Support of Network Slicing, and xi) SMF selection.

The User Plane Function (UPF) hosts the following main functions: i) Anchor point for Intra-/Inter-RAT mobility (when applicable), ii) External PDU session point of interconnect to Data Network, iii) Packet inspection and User plane part of Policy rule enforcement, iv) Traffic usage reporting, v) Uplink classifier to support routing traffic flows to a data network, vi) QoS handling for user plane, e.g. packet filtering, gating, UL/DL rate enforcement, and vii) Uplink Traffic verification (SDF to QoS flow mapping).

The Session Management function (SMF) hosts the following main functions: i) Session Management, ii) UE IP address allocation and management, iii) Selection and control of UP function, iv) Configures traffic steering at UPF to route traffic to proper destination, v) Control part of policy enforcement and QoS, vi) Downlink Data Notification.

FIG. 5 is a diagram showing a control plane and a user plane of a radio interface protocol between a UE and a NG-RAN based on a 3rd generation partnership project (3GPP) radio access network standard.

The user plane protocol stack contains Phy, MAC, RLC, PDCP and SDAP (Service Data Adaptation Protocol) which is newly introduced to support 5G QoS model.

The main services and functions of SDAP entity include i) Mapping between a QoS flow and a data radio bearer, and ii) Marking QoS flow ID (QFI) in both DL and UL packets. A single protocol entity of SDAP is configured for each individual PDU session.

At the reception of an SDAP SDU from upper layer for a QoS flow, the transmitting SDAP entity may map the SDAP SDU to the default DRB if there is no stored QoS flow to DRB mapping rule for the QoS flow. If there is a stored QoS flow to DRB mapping rule for the QoS flow, the SDAP entity may map the SDAP SDU to the DRB according to the stored QoS flow to DRB mapping rule. And the SDAP entity may construct the SDAP PDU and deliver the constructed SDAP PDU to the lower layers.

FIG. 6 is a block diagram of a communication apparatus according to an embodiment of the present invention.

The apparatus shown in FIG. 6 can be a user equipment (UE) and/or eNB or gNB adapted to perform the above mechanism, but it can be any apparatus for performing the same operation.

As shown in FIG. 6, the apparatus may comprises a DSP/microprocessor (110) and RF module (transceiver; 135). The DSP/microprocessor (110) is electrically connected with the transceiver (135) and controls it. The apparatus may further include power management module (105), battery (155), display (115), keypad (120), SIM card (125), memory device (130), speaker (145) and input device (150), based on its implementation and designer's choice.

Specifically, FIG. 6 may represent a UE comprising a receiver (135) configured to receive a request message from a network, and a transmitter (135) configured to transmit the transmission or reception timing information to the network. These receiver and the transmitter can constitute the transceiver (135). The UE further comprises a processor (110) connected to the transceiver (135: receiver and transmitter).

Also, FIG. 6 may represent a network apparatus comprising a transmitter (135) configured to transmit a request message to a UE and a receiver (135) configured to receive the transmission or reception timing information from the UE. These transmitter and receiver may constitute the transceiver (135). The network further comprises a processor (110) connected to the transmitter and the receiver. This processor (110) may be configured to calculate latency based on the transmission or reception timing information.

FIG. 7 is a diagram for signaling of power headroom reporting via a MAC CE.

The amount of transmission power available in each UE is also relevant for the uplink scheduler. Obviously, there is little reason to schedule a higher data rate than the available transmission power can support. In the downlink, the available power is immediately known to the scheduler as the power amplifier is located in the same node as the scheduler. For the uplink, the power availability, or power headroom is defined as the difference between the nominal maximum output power and the estimated output power for UL-SCH transmission.

This quantity can be positive as well as negative (on a dB scale), where a negative value would indicate that the network has scheduled a higher data rate than the terminal can support given its current power availability. The power headroom depends on the power-control mechanism and thereby indirectly on factors such as the interference in the system and the distance to the base stations. Information about the power headroom is fed back from the terminals to the eNodeB in a similar way as the buffer-status reports—that is, only when the terminal is scheduled to transmit on the UL-SCH.

A Power Headroom Report (PHR) shall be triggered if any of the following events occur: i) prohibitPHR-Timer expires or has expired and the path loss has changed more than dl-PathlossChange dB for at least one activated Serving Cell of any MAC entity which is used as a pathloss reference since the last transmission of a PHR in this MAC entity when the MAC entity has UL resources for new transmission; ii) periodicPHR-Timer expires; iii) upon configuration or reconfiguration of the power headroom reporting functionality by upper layers, which is not used to disable the function; iv) activation of an SCell of any MAC entity with configured uplink, v) addition of the PSCell, vi) prohibitPHR-Timer expires or has expired, when the MAC entity has UL resources for new transmission, and the following is true in this TTI for any of the activated Serving Cells of any MAC entity with configured uplink: there are UL resources allocated for transmission or there is a PUCCH transmission on this cell, and the required power backoff due to power management for this cell has changed more than dl-PathlossChange dB since the last transmission of a PHR when the MAC entity had UL resources allocated for transmission or PUCCH transmission on this cell.

It is also possible to configure a prohibit timer to control the minimum time between two power-headroom reports and thereby the signaling load on the uplink.

If the MAC entity has UL resources allocated for new transmission for this TTI the MAC entity shall start periodicPHR-Timer if it is the first UL resource allocated for a new transmission since the last MAC reset. If the Power Headroom reporting procedure determines that at least one PHR has been triggered and not cancelled, the MAC entity shall obtain the value of the Type 1 power headroom from the physical layer, and instruct the Multiplexing and Assembly procedure to generate and transmit a PHR MAC control element based on the value reported by the physical layer. And the MAC entity start or restart periodicPHR-Timer, start or restart prohibitPHR-Timer, and cancel all triggered PHR.

For the uplink transmission, the UE uses the PHR in order to provide the network with information about the difference between the nominal maximum transmit power and the estimated required transmit power. Thus, PHR indicates how much transmission power can be additionally used from the UE side.

In LTE, the Power Headroom Report (PHR) MAC control element is identified by a MAC PDU subheader with LCID as specified in Table 1. It has a fixed size and consists of a single octet defined as follows (FIG. 7a ):

TABLE 1 Index LCID values 00000 CCCH 00001-01010 Identity of the logical channel 01011 CCCH 01100 CCCH 01101-10011 Reserved 10100 Recommended bit rate query 10101 SPS confirmation 10110 Truncated Sidelink BSR 10111 Sidelink BSR 11000 Dual Connectivity Power Headroom Report 11001 Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI 11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

‘R’ is reserved bit, set to “0”;

Power Headroom (PH) field indicates the power headroom level. The length of the field is 6 bits. The reported PH and the corresponding power headroom levels are shown in Table 2;

TABLE 2 PH Power Headroom Level 0 POWER_HEADROOM_0 1 POWER_HEADROOM_1 2 POWER_HEADROOM_2 3 POWER_HEADROOM_3 . . . . . . 60 POWER_HEADROOM_60 61 POWER_HEADROOM_61 62 POWER_HEADROOM_62 63 POWER_HEADROOM_63

For extendedPHR, the Extended Power Headroom Report (PHR) MAC control element is identified by a MAC PDU subheader with LCID as specified in Table 1. It has a variable size and is defined in FIGS. 7b and 7c . When Type 2 PH is reported, the octet containing the Type 2 PH field is included first after the octet indicating the presence of PH per SCell and followed by an octet containing the associated P_(CMAX,c) field (if reported). Then follows an octet with the Type 1 PH field and an octet with the associated P_(CMAX,c) field (if reported), for the PCell. And then follows in ascending order based on the ServCelllndex an octet with the Type x PH field, wherein x is equal to 3 when the ul-Configuration-r14 is configured for this SCell, x is equal to 1 otherwise, and an octet with the associated P_(CMAX,c) field (if reported), for each SCell indicated in the bitmap.

When the highest SCellIndex of SCell with configured uplink is less than 8, one octet with C fields is used for indicating the presence of PH per SCell (FIG. 7b ), Otherwise, four octets are used (FIG. 7c ).

The UE determines whether PH value for an activated Serving Cell is based on real transmission or a reference format by considering the downlink control information which has been received until and including the PDCCH occasion in which the first UL grant is received since a PHR has been triggered.

FIG. 7b is an example for Extended PHR MAC Control Elements with the highest SCelllndex of SCell with configured uplink is less than 8, and FIG. 7c is an example for Extended PHR MAC Control Elements with the highest SCelllndex of SCell with configured uplink is equal to or higher than 8.

The PHR MAC CEs are defined as follows:

‘Ci field’ indicates the presence of a PH field for the SCell with SCellIndex i. The Ci field set to “1” indicates that a PH field for the SCell with SCellIndex i is reported. The Ci field set to “0” indicates that a PH field for the SCell with SCellIndex i is not reported.

‘V field’ indicates if the PH value is based on a real transmission or a reference format. For Type 1 PH, V=0 indicates real transmission on PUSCH and V=1 indicates that a PUSCH reference format is used. For Type 2 PH, V=0 indicates real transmission on PUCCH and V=1 indicates that a PUCCH reference format is used. For Type 3 PH, V=0 indicates real transmission on SRS and V=1 indicates that an SRS reference format is used. Furthermore, for Type 1, Type 2, and Type 3 PH, V=0 indicates the presence of the octet containing the associated P_(CMAX,c) field, and V=1 indicates that the octet containing the associated P_(CMAX,c) field is omitted.

‘PH field’ indicates the power headroom level. The length of the field is 6 bits. The reported PH and the corresponding power headroom levels are shown in Table 2.

‘P field’ indicates whether the MAC entity applies power backoff due to power management. The MAC entity shall set P=1 if the corresponding P_(CMAX,c) field would have had a different value if no power backoff due to power management had been applied.

P_(CMAX,c): if present, this field indicates the P_(CMAX,c) or {tilde over (P)}_(CMAX,c) used for calculation of the preceding PH field. The reported P_(CMAX,c) and the corresponding nominal UE transmit power levels are shown in Table 3

TABLE 3 P_(CMAX, c) Nominal UE transmit power level 0 PCMAX_C_00 1 PCMAX_C_01 2 PCMAX_C_02 . . . . . . 61 PCMAX_C_61 62 PCMAX_C_62 63 PCMAX_C_63

In NR, the Single Entry PHR MAC CE is identified by a MAC PDU subheader with LCID as specified in Table 4. It has a fixed size and consists of two octet defined as follows (FIG. 7d ):

TABLE 4 Index LCID values 000000 CCCH 000001-100000 Identity of the logical channel 100001-110110 Reserved 110111 Configured Grant Confirmation 111000 Multiple Entry PHR 111001 Single Entry PHR 111010 C-RNTI 111011 Short Truncated BSR 111100 Long Truncated BSR 111101 Short BSR 111110 Long BSR 111111 Padding

‘R’ is reserved bit, set to “0”;

Power Headroom (PH) field indicates the power headroom level. The length of the field is 6 bits. The reported PH and the corresponding power headroom levels are shown in Table 5;

TABLE 5 PH Power Headroom Level 0 POWER_HEADROOM_0 1 POWER_HEADROOM_1 2 POWER_HEADROOM_2 3 POWER_HEADROOM_3 . . . . . . 60 POWER_HEADROOM_60 61 POWER_HEADROOM_61 62 POWER_HEADROOM_62 63 POWER_HEADROOM_63

P_(CMAX,c) field indicates the P_(CMAX,c) used for calculation of the preceding PH field. The reported P_(CMAX,c) and the corresponding nominal UE transmit power levels are shown in Table 6.

TABLE 6 P_(CMAX, c) Nominal UE transmit power level 0 PCMAX_C_00 1 PCMAX_C_01 2 PCMAX_C_02 . . . . . . 61 PCMAX_C_61 62 PCMAX_C_62 63 PCMAX_C_63

The Multiple Entry PHR MAC CE is identified by a MAC PDU subheader with LCID as specified in Table 4. It includes the bitmap, a Type 2 PH field and an octet containing the associated P_(CMAX,c) field (if reported) for the PCell, a Type 2 PH field and an octet containing the associated P_(CMAX,c) field (if reported) for either PSCell or PUCCH SCell, a Type 1 PH field and an octet containing the associated P_(CMAX,c) field (if reported) for the PCell. It further includes, in ascending order based on the ServCelllndex, one or multiple of Type 1 PH fields and octets containing the associated P_(CMAX,c) fields (if reported) for SCells indicated in the bitmap.

The presence of Type 2 PH field for PCell is configured by phr-Type2PCell, and the presence of Type 2 PH field for either PSCell or for PUCCH SCell is configured by phr-Type2OtherCell.

A single octet bitmap is used for indicating the presence of PH per SCell when the highest SCellIndex of SCell with configured uplink is less than 8, otherwise four octets are used.

The UE determines whether PH value for an activated Serving Cell is based on real transmission or a reference format by considering the downlink control information which has been received until and including the PDCCH occasion in which the first UL grant is received since a PHR has been triggered.

FIG. 7e is an example for Multiple Entry PHR MAC CE with the highest SCellIndex of SCell with configured uplink is less than 8, and FIG. 7f is an example for Multiple Entry PHR MAC CE with the highest SCellIndex of SCell with configured uplink is equal to or higher than 8.

The PHR MAC CEs are defined as follows:

‘Ci field’ indicates the presence of a PH field for the SCell with SCellIndex i. The Ci field set to “1” indicates that a PH field for the SCell with SCellIndex i is reported. The Ci field set to “0” indicates that a PH field for the SCell with SCellIndex i is not reported.

‘V field’ indicates if the PH value is based on a real transmission or a reference format. For Type 1 PH, V=0 indicates real transmission on PUSCH and V=1 indicates that a PUSCH reference format is used. For Type 2 PH, V=0 indicates real transmission on PUCCH and V=1 indicates that a PUCCH reference format is used. For Type 3 PH, V=0 indicates real transmission on SRS and V=1 indicates that an SRS reference format is used. Furthermore, for Type 1, Type 2, and Type 3 PH, V=0 indicates the presence of the octet containing the associated P_(CMAX,c) field, and V=1 indicates that the octet containing the associated P_(CMAX,c) field is omitted.

‘PH field’ indicates the power headroom level. The length of the field is 6 bits. The reported PH and the corresponding power headroom levels are shown in Table 2 (the corresponding measured values in dB for the NR Serving Cell are specified in TS 38.133 while the corresponding measured values in dB for the LTE Serving Cell are specified in TS 36.133).

‘P field’ indicates whether the MAC entity applies power backoff due to power management. The MAC entity shall set P=1 if the corresponding P_(CMAX,c) field would have had a different value if no power backoff due to power management had been applied.

P_(CMAX,c): if present, this field indicates the P_(CMAX,c) or {tilde over (P)}_(CMAX,c) used for calculation of the preceding PH field. The reported P_(CMAX,c) and the corresponding nominal UE transmit power levels are shown in Table 6 (the corresponding measured values in dB for the NR Serving Cell are specified in TS 38.133 while the corresponding measured values in dB for the LTE Serving Cell are specified in TS 36.133).

FIG. 8a is examples for multiple beam pair links, and FIG. 8b is an example of PHR trigger in BWP activation/deactivation.

To provide link robustness between UE and gNB for both downlink and uplink, there may be multiple beam pair links between UE and gNB, where a beam pair link comprises a UE TX beam and a gNB RX beam. By using the multiple beam pair links, the UE may be able to transmit or receive a data repeatedly, if necessary. RAN1 agreed that UE should be able to maintain links with multiple DL beam pair of one cell between multiple TRPs and the UE. For UL link robustness, it would be necessary to maintain multiple UL beam pair links between multiple TRPs and the UE. In particular, pathloss between multiple TRPs may be significantly different than pathloss in multiple links within a single TRP due to their locations. This may result in different resource allocations e.g., including transmit power, between multiple beam pair links. The gNB should allocate the suitable UL resource for each beam pair based on the UE's PH information. The FIG. 8a describes the examples for multiple beam pair links.

Meanwhile, similar to the multi-beam case, gNB may have to allocate the suitable UL resource for each bandwidth part of a UE. To provide a variety of services, NR supports the wider bandwidth composed of multiple bandwidth parts with a different numerology. RAN1 agreed that the at least one DL bandwidth part and one UL bandwidth part is activated among the set of configured bandwidth parts for a given time instant. Also, RAN1 agreed to primarily focus on the single active bandwidth part case.

Currently, RAN1 has three alternatives to discuss how to activate/deactivate the DL/UL bandwidth parts, i.e., by means of DCI (Downlink Control Information), RRC signaling or MAC CE. Similar to the CA or DC in LTE, the PHR in NR may be defined to be triggered by the BWP activation. If the BWPs is activated/deactivated by the DCI, since the BWP activation/deactivation would be dynamically performed by gNB, the PHR transmission will occur very frequently. The FIG. 8b describes an example of the frequent PHR trigger in case of BWP dynamic activation. In order to prevent the frequent PHR transmissions, we prefer to trigger PHR when the BWPs are configured for a UE. In this case, as each numerology may experience different radio condition, PH for different numerology would have a different value.

Therefore, for accurate power control, it may be necessary for the UE to report PHs for all configured numerologies even if the bandwidth part for the numerology is actually not activated.

FIG. 9 is a conceptual diagram for transmitting a power headroom reporting in wireless communication system according to embodiments of the present invention.

When the UE is configured with one or more BWPs per serving cell, the UE triggers a Power Headroom reporting (PHR) when a BWP is (re) configuration, activation, switching or deactivation (S901).

First, the UE can be a PHR when BWP(s) is (re)configured.

In WB operation, the gNB can configure one or more BWP(s) for a CC of UE. This means that one or more BWP(s) could be allocated/(re)configured to a UE while/after gNB activates CC with WB, but before activating the specific DL/UL BWP. After BWP configuration, the gNB can activate or deactivate a specific BWP for a UE.

So, our invention proposes to trigger the PHR when BWP(s) of a UE is configured by gNB. If the BWP activation/deactivation is indicated by means of Downlink Control Information (DCI), i.e., dynamic BWP activation/deactivation, the PHR may be very frequently triggered since the prohibit timer would be independently performed with the PHR trigger event for BWP activation. So, in case of dynamic BWP activation/deactivation, it would be preferable that BWP configuration is used for PHR trigger event. If a BWP is configured at the same time as the serving cell activation, it would be preferable that the PHR is triggered when BWP is reconfigured.

Secondly, the UE can be a PHR when a (Secondary) BWP(s) is activated or deactivated. In WB operation, the gNB can activate or deactivate one or more BWP(s) for a UE. This means that a UE can transmit/receive data on the BWP(s) activated by any indication. So, our invention proposes to trigger the PHR when BWP(s) of a UE is newly activated or deactivated by the gNB. If a primary BWP is activated at the same time as the serving cell activation, it would be preferable that the PHR is triggered when a secondary BWP is activated.

Lastly, the UE can be a PHR when BWP is switched. In WB operation, the gNB can activate a single BWP for a UE at a given time instant. This means that a UE can transmit/receive data on a single BWP and gNB may indicate to switch from one BWP to another BWP (or to activate a new BWP) if it needs to activate another BWP. The purpose of the BWP switching command is to change an active BWP used in a particular cell. That is, the BWP switching command is for switching active BWP.

Currently, the UE is configured with four BWPs per cell, and only one of them will be in active state. When a BWP switching command is received via DCI, the UE deactivates the active BWP and activates the new BWP autonomously (i.e, there is no BWP deactivation command). Our invention proposes to trigger the PHR when a BWP of UE is switched to another BWP by gNB.

When the PHR is triggered, the UE generates a Power Headroom Reporting (PHR) Medium Access Control (MAC) Control Element (CE) including multiple PH fields for a serving cell, and an octet containing a single P_(CMAX) field associated with the multiple PH fields for the serving cell (S903). And the UE transmits the PHR MAC CE to a network (S905).

For example, in a state that the gNB configures a component carrier (e.g., SCell) with wider bandwidth for UE, the gNB (re)configures one or more BWPs for UE during or after SCell activation. When BWPs are (re)configured by gNB, the UE transmits PHR including PH information for configured BWPs (B₀, B₁).

For the deactivated B₁, the UE can calculate the PH value based on the reference format. For the activated B₀, the UE can calculate the PH value based on a real transmission.

Although the gNB activates or deactivates a configured BWP for a UE, the UE transmits the PHR only when a PHR trigger event is met, e.g., PHR periodic timer expiry, pathloss changes more than threshold after PHR prohibit timer expiry, configuration of PHR functionality, Scell activation, PSCell addition, etc.

FIG. 10 is an example of PHR trigger based on the BWP configuration.

Although only BWP is described, beam pair can be applied similarly.

When the UE is configured with one or more BPs per serving cell, the UE triggers a Power Headroom reporting (PHR) when a BP is (re) configuration, activation, switching or deactivation (S901).

First, the UE can be a PHR when BP(s) is (re)configured.

In multiple beam operation, the gNB can configure one or more BP(s) for a CC of UE. This means that one or more BP(s) could be allocated/(re)configured to a UE while/after gNB activates CC with multi-beam, but before activating the specific DL/UL BP. After BP configuration, the gNB can activate or deactivate a specific BP for a UE.

So, our invention proposes to trigger the PHR when BP(s) of a UE is configured by gNB. If the BP activation/deactivation is indicated by lower layer, the PHR may be very frequently triggered since the prohibit timer would be independently performed with the PHR trigger event for BP activation. If a BP is configured at the same time as the serving cell activation, it would be preferable that the PHR is triggered when BP is reconfigured.

Secondly, the UE can be a PHR when a BP(s) is activated or deactivated. In multi beam operation, the gNB can activate or deactivate one or more BP(s) for a UE. This means that a UE can transmit/receive data on the BP(s) activated by any indication. So, our invention proposes to trigger the PHR when BP(s) of a UE is newly activated or deactivated by the gNB.

Lastly, the UE can be a PHR when BP is switched. In multi beam operation, the gNB can activate a single BP for a UE at a given time instant. This means that a UE can transmit/receive data on a single BP and gNB may indicate to switch from one BP to another BWP (or to activate a new BP) if it needs to activate another BP. Our invention proposes to trigger the PHR when a BP of UE is switched to another BP by gNB.

When the PHR is triggered, the UE generates a Power Headroom Reporting (PHR) Medium Access Control (MAC) Control Element (CE) including multiple PH fields for a serving cell, and an octet containing a single P_(CMAX) field associated with the multiple PH fields for the serving cell (S903). And the UE transmits the PHR MAC CE to a network (S905).

For example, in a case that the UE performs the beam management, the gNB configures one or more UL beam pair (i.e., UE Tx beam and gNB Rx beam) for a UE. This beam management can include beam measurement and reporting the measurement results.

The gNB can allocate the UL resources for multi-BP of a UE. The resources would be time domain multiplexed.

When one or more UL beam pair is (re)allocated/activated by gNB and PHR trigger event is met, the UE transmits PHR including PH information for activated BPs (B₀, B₁).

At the time instant of PHR transmission, for the B₁ without the allocated UL resource, the UE can calculate the PH value based on the reference format. At the time instant of PHR transmission, for the B₀ with the allocated UL resource, the UE can calculate the PH value based on a real transmission.

Theses formats A to C, described in detail below, are used in a case where multiple bandwidth parts are configured to a UE and the bandwidth part is dynamically activated/deactivated by DCI, or another case where UL multiple beam pairs are allocated to a UE and the resources for different UL BPs are multiplexed in the time domain.

FIGS. 11 and 12 are examples for a PHR MAC CE for BP or BWP operation (format A) according to embodiments of the present invention.

This invention proposes that a UE transmits one or more PH(s) for a single P_(CMAX, C) field in PHR MAC CE in order to inform each PH for different UL beam pair (hereinafter, referred to as BP) or different numerology/bandwidth part (hereinafter, referred to as BWP) of a serving cell.

In particular, this invention proposes to define a new PHR MAC CE format including an octet containing a single P_(CMAX) field associated with the multiple PH fields for the serving cell.

In this case, the single P_(CMAX) field is used for calculation of the preceding multiple PH fields.

The PH information for each BP/BWP can mean P, V and PH value for Type X.

Preferably, in this case, the multiple PH fields are a same type of PH.

This format A proposes to define a PH bitmap per serving cell to indicate whether at least two PH information for different BP/BWP are present or not. The PH bitmap for a specific Ci is present if the Ci field is set to 1. That is the PH bitmap is present when the serving cell is activated.

The PH bitmap for the primary cell may be always located after the octet containing Ci fields (Ci bitmap) or the indication bit (C₀) for PCell may be defined to indicate whether PH bitmap of PCell is present or not.

Here, we assume that the maximum number of the configured UL BP(s)/BWP(s) is set to j and the length of each PH bitmap is defined to j (or j−1) bits, where j is an integer value greater than zero.

If the bit (Bj) corresponding to a certain BP/BWP index is set to 1, PH information for the BP/BWP are transmitted by UE. If Bj field is set to 1, in descending or ascending order of the Bj set to 1, corresponding PH information are defined before the P_(CMAX, C).

If Ci field is set to 1, in descending or ascending order of the Ci set to 1, corresponding PH bitmap follows after the Ci bitmap, as shown in the FIG. 11.

Alternatively, if Ci field is set to 1, the PH bitmap for the serving cell follows before the first PH information of the serving cell as shown in the FIG. 12.

In addition, if Ci field is set to 1, the PH bitmap for the serving cell can follow right after each Ci. The PH bitmap can be located in a variety of ways not described here.

Here, the indication bit (B₀) for the primary BP/BWP of each cell can be omitted since the primary BP/BWP may be always present if the serving cell is present.

Format A benefits that the processing can be performed more efficiently at the receiving end, since the proposed PHR MAC CE includes an octet containing the BWP bitmap is included first after an octet containing the Ci bitmap and followed by an octet containing PH information. Further, Format A reports all of the active BWP PHs for the active cell, so it is advantageous for the base station to know the PH of each BWP accurately.

FIG. 13 is an example for a PHR MAC CE for BP or BWP operation (format B) according to embodiments of the present invention.

This Format B proposes that a UE transmits the configured/fixed number of PH information for each serving cell. Here, the PH information consists of P, V and PH for type x.

Since every serving cell may not consist of more than one BP/BWP, in order to reduce the signalling overhead, we also propose to define the PH bitmap (PBi) to indicate whether two or more PH information for the serving cell (Ci) are present or not.

That is, when the number of PH that can be reported for a certain serving cell is fixed to a specific value, the PH bitmap is always located after the octet containing Ci fields (Ci bitmap) and a length of the PH bitmap is equal to a number of configured serving cells, e.g., based on LTE, the length of PH bitmap can be 8 or 32.

If the Ci bit for the serving cell is set to 1, the gNB should check whether the corresponding Bi bit is set to 1 or 0. Based on LTE, gNB would always check the indication bit (PB0) for the primary cell. If the corresponding PBi bit is also set to 1, the fixed number (j, where j is an integer value greater than zero) of PHs are defined in the PH section for the serving cell as described in FIG. 13.

From a UE perspective, if a UE needs to inform at least two PHs for a certain serving cell, the UE should set the Ci and PBi bit corresponding to the serving cell and contain PH list for the configured BP/BWPs and one P_(CMAX, c) for the serving cell.

The each PH for a BP/BWP can be located in a variety of rules not described here.

The Format B is useful when the number of multiple PHs that can be reported for a serving cell is fixed, because the PHR MAC CE contains one octet containing the Bi field, thereby reducing signal overhead.

FIG. 14 is an example for a PHR MAC CE for BP or BWP operation (format C) according to embodiments of the present invention.

The format C proposes to newly define BP/BWP index field in the PHR MAC CE.

This scheme proposes to define BP/BWP index field in the PHR MAC CE, if an additional PH information for a serving cell is present. If the gNB needs to know whether the additional PH information for each BP/BWP is present or not, it also proposes to define a PH extension field in the PHR MAC CE.

The PH extension field indicates whether an additional PH information with BP/BWP index is present or not. It will be 1-bit length.

If the PH extension is set to 1, an additional PH with the BP/BWP index is transmitted by UE. Here, we assume that the length of a BP/BWP index can be defined to j bits according to the maximum number of the configured BP/BWP, where j is an integer value greater than zero.

The PH extension field can be defined using the reserved bit before each P_(CMAX, c) and after/before the BP/BWP index, as shown in the FIG. 14.

If the PH extension filed is set to 1, the BP/BWP index and corresponding PH information are included after the P_(CMAX,c) field for the cell. The proposed PH extension and BWP index can be located in a variety of ways not described here.

Format C is advantageous in a cased that the UE is configured with many BWPs per cell (e.g, a 4-bit or 8-bit bitmap or longer BWP bitmap field is needed). That is, there is an advantage in view of transmission overhead.

The PHR triggered by the new triggering events described above may use the new PHR MAC CE proposed in formats A to C of the present inventions.

Since the value of P_(CMAX,c) field may be dependent on a serving cell, it is likely that it will have the same P_(CMAX,c) value even if there are several BPs or several BWPs in the serving cell. The present invention can be usefully used in such cases. According to the present invention, since one P_(CMAX,c) is used for calculation of multiple PH information, the reporting amount of the PHR MAC CE can be reduced.

The embodiments of the present invention described hereinbelow are combinations of elements and features of the present invention. The elements or features may be considered selective unless otherwise mentioned. Each element or feature may be practiced without being combined with other elements or features. Further, an embodiment of the present invention may be constructed by combining parts of the elements and/or features. Operation orders described in embodiments of the present invention may be rearranged. Some constructions of any one embodiment may be included in another embodiment and may be replaced with corresponding constructions of another embodiment. It is obvious to those skilled in the art that claims that are not explicitly cited in each other in the appended claims may be presented in combination as an embodiment of the present invention or included as a new claim by subsequent amendment after the application is filed.

In the embodiments of the present invention, a specific operation described as performed by the BS may be performed by an upper node of the BS. Namely, it is apparent that, in a network comprised of a plurality of network nodes including a BS, various operations performed for communication with an MS may be performed by the BS, or network nodes other than the BS. The term ‘eNB’ may be replaced with the term ‘fixed station’, ‘Node B’, ‘Base Station (BS)’, ‘access point’, etc.

The above-described embodiments may be implemented by various means, for example, by hardware, firmware, software, or a combination thereof.

In a hardware configuration, the method according to the embodiments of the present invention may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microcontrollers, or microprocessors.

In a firmware or software configuration, the method according to the embodiments of the present invention may be implemented in the form of modules, procedures, functions, etc. performing the above-described functions or operations. Software code may be stored in a memory unit and executed by a processor. The memory unit may be located at the interior or exterior of the processor and may transmit and receive data to and from the processor via various known means.

Those skilled in the art will appreciate that the present invention may be carried out in other specific ways than those set forth herein without departing from essential characteristics of the present invention. The above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by the appended claims, not by the above description, and all changes coming within the meaning of the appended claims are intended to be embraced therein.

INDUSTRIAL APPLICABILITY

While the above-described method has been described centering on an example applied to the 3GPP LTE and NR system, the present invention is applicable to a variety of wireless communication systems in addition to the 3GPP LTE and NR system. 

The invention claimed is:
 1. A method performed by a User Equipment (UE) operating in a wireless communication system, the method comprising: generating a Power Headroom Reporting (PHR) Medium Access Control (MAC) Control Element (CE) including multiple Power Headroom (PH) fields for a serving cell; and transmitting the PHR MAC CE, wherein the PHR MAC CE includes an octet containing a single P_(CMAX) field associated with the multiple PH fields for the serving cell, wherein the UE operates in multiple-Bandwidth Part (BWP) operation, wherein the PHR MAC CE includes a BWP bitmap indicating presence of a PH field per BWP within the serving cell, and wherein the BWP bitmap includes one or more fields, each of the one or more fields corresponding to a respective BWP with an index j, and indicating presence of a PH field for the respective BWP identified by the index j.
 2. The method according to claim 1, wherein the multiple PH fields associated with the single P_(CMAX) field are a same type of PH.
 3. The method according to claim 1, further comprising: triggering a PHR for generating the PHR MAC CE based on at least one of: (i) a BWP being newly configured, (ii) a configured BWP being activated or deactivated, or (iii) a configured BWP being switched.
 4. The method according to claim 1, wherein the single P_(CMAX) field includes power information used for calculation of the associated multiple PH fields.
 5. The method according to claim 1, wherein the UE is capable of communicating with at least one of another UE, a UE related to an autonomous driving vehicle, a base station and/or a network.
 6. A User Equipment (UE) configured to operate in a wireless communication system, the UE comprising: a Radio Frequency (RF) module; and a processor operably coupled with the RF module and configured to: generate a Power Headroom Reporting (PHR) Medium Access Control (MAC) Control Element (CE) including multiple Power Headroom (PH) fields for a serving cell, and transmit the PHR MAC CE, wherein the PHR MAC CE includes an octet containing a single P_(CMAX) field associated with the multiple PH fields for the serving cell, wherein the UE operates in multiple-Bandwidth Part (BWP) operation, wherein the PHR MAC CE includes a BWP bitmap indicating presence of a PH field per BWP within the serving cell, and wherein the BWP bitmap includes one or more fields, each of the one or more fields corresponding to a respective BWP with an index j, and indicating presence of a PH field for the respective BWP identified by the index j.
 7. The UE according to claim 6, wherein the multiple PH fields associated with the single P_(CMAX) field are a same type of PH.
 8. The UE according to claim 6, wherein the processor is further configured to: trigger a PHR for generating the PHR MAC CE based on at least one of: (i) a BWP being newly configured, (ii) a configured BWP being activated or deactivated, or (iii) a configured BWP being switched.
 9. The UE according to claim 6, wherein the single P_(CMAX) field includes power information used for calculation of the associated multiple PH fields.
 10. The UE according to claim 6, wherein the UE is capable of communicating with at least one of another UE, a UE related to an autonomous driving vehicle, a base station and/or a network. 